Phonon-assisted radiative electron-hole recombination in silicon quantum dots

Abstract

The temperature dependence of the photoluminescence (PL) spectrum of silicon quantum dots (QDs) is studied both theoretically and experimentally, and the time of the corresponding electron-hole radiative recombination is calculated. The dependence of the recombination time on the QD size is discussed. The experiment shows that the PL intensity decreases by approximately 60% as the temperature increases from 77 to 293 K. The calculated characteristic recombination time has only a weak temperature dependence; therefore, the decrease in the PL intensity is associated primarily with nonradiative transitions. It is also shown that the phonon-assisted radiation is much more efficient than the zero-phonon emission. Moreover, the zero-phonon recombination time depends on the QD radius R as R8, whereas the phonon-assisted recombination time depends on this radius as R3.